Narrow Tube Research Articles

An analytical model for solute transport from blood to tissue

Abstract For narrow tubes, red blood cells concentrate in the core region, leaving an annular zone called cell-free layer. This has an impact on both the tube hematocrit level (Fåhraeus effect) and the apparent blood viscosity (Fåhraeus–Lindqvist effect). Blood flow, mass transfer across the microvessel membrane, and diffusion in the tissue affect the solute concentration profiles. The Krogh tissue cylinder concept, limiting mass transfer to a cylinder around each microvessel, and the marginal zone concept (introduced by Haynes to analyze blood flow dynamics in narrow tubes) are both used to develop a model for solute transfer from blood in microvessels to the surrounding tissues, based on fundamentals. The analysis accounts for advection and diffusion in each zone of the microvessel, solute transport in the microvessel membranes, and diffusion and reaction in the tissues. The present investigation provides an analytical solution. The approach can be extended to treat other kinetic models, while accounting for Fåhraeus and Fåhraeus–Lindqvist effects in blood microvessels. The model is validated against published results for glucose transport from blood to tissue.

Effects of a significant boundary layer on the flame acceleration and transition to detonation in millimeter-scale tubes

Experiments using three different mixtures (ethylene–oxygen, methane–oxygen, and acetylene–oxygen–argon) and four different tube diameters (0.5, 1, 2, and 4 mm) were carried out to investigate the entire process of flame propagation in narrow tubes. Flame propagation in the four sizes of tubes was recorded synchronously by a high-speed camera. The results show that the deflagration-to-detonation transition (DDT) process goes through four stages according to velocity evolution, in the sequence of (i) exponential acceleration, (ii) “hesitation” period, (iii) linear acceleration, and (iv) velocity jump. The DDT run-up distance decreases with decreasing tube diameter, which arises from the effect of the significant boundary layer during flame acceleration. The area divergence is introduced by analyzing how tube diameter and initial pressure affect the DDT run-up distance. The critical value of 0.1 for the area divergence can be used to distinguish the variation characteristics of the normalized DDT run-up distance between millimeter-scale tubes and the large tubes (centimeter-scale). Moreover, an empirical formula with a unified form is obtained, which describes the DDT run-up distance as a function of tube diameter and initial pressure. It allows a good prediction of the experimental results regardless of the tube size as well as the type of mixture.

Floral biology, floral volatile organic compounds and floral visitors of Chromolaena odorata, an invasive alien species in West Bengal, India

Abstract. Layek U, Das A, Das U. 2022. Floral biology, floral volatile organic compounds and floral visitors of Chromolaena odorata, an invasive alien species in West Bengal, India. Biodiversitas 23: 2118-2129. Chromolaena odorata (L.) R.M. King & H. Rob. is a fast-growing weed native to the Neotropics and introduced in several regions of Africa, the Pacific Islands, and Southeast Asia, including West Bengal in India. It is one of the world’s most widespread and troublesome invasive alien plant species (IAPS) that severely infest natural habitats and crop fields. However, extensive data documents about the reproductive ecology are unknown, especially within West Bengal. This study assesses the floral biology, floral volatile organic compounds (VOCs), and floral visitors of the weed. The weed species flowers from October to January. Florets are white to purple, with short, narrow corolla tubes and deep-seated nectar. Abundant VOCs are benzyl stearate, 2,4-decadienal, n-hexadecanoic acid, 1-hexyl-2-nitrocyclohexane, and o-decyl hydroxylamine. Flower heads were visited by numerous insect groups, though the diversity of Lepidoptera (mainly butterflies) was higher than the other insect orders. The weed is pollinated by diverse insect groups (e.g., butterflies, flies, honeybees, leafcutter bees, solitary bees, and wasps). However, vital pollination services to the weed were provided by butterflies (based on the ‘approximate pollination value’). Our findings may conclude that the clustered capitula, longer stigmatic receptivity, and broad array of pollinators resulted in too much fruit set. It is one of the critical factors that support the high growth rate and invasive nature of the weed in dry habitats.

On Diffusion Processes with Drift in Ld+ 1

This paper is a natural continuation of Krylov (2020 and 2021) where strong Markov processes are constructed in time inhomogeneous setting with Borel measurable uniformly bounded and uniformly nondegenerate diffusion and drift in $L_{d+1}(\mathbb {R}^{d+1})$ and some properties of their Green’s functions and probability of passing through narrow tubes are investigated. On the basis of this here we study some further properties of these processes such as Harnack inequality, Hölder continuity of potentials, Fanghua Lin estimates and so on.

Analytical model of a short DC glow discharge in the presence of significant radial ambipolar diffusion losses

We present a simple analytical model of a short direct-current glow discharge (without positive column) that is applicable for the case of narrow discharge tubes when radial losses of charged particles due to ambipolar diffusion significantly influence discharge properties. The model is based on the analytical parameterization of the non-local ionization produced by fast electrons, which allows obtaining an exact solution of the ambipolar diffusion equation with radial particle losses written in the τ-approximation. Analysis of the spatial distribution of electron density in the near-cathode plasma regions of a discharge allow obtaining an explicit expression for the position of electric field reversal in the negative glow that is independent of electron temperature and interelectrode distance. The latter fact makes the model viable for description of near-cathode plasma regions in the general case of a discharge with a positive column. The procedure for obtaining quantitative estimates and interpretation of experimental data on discharge properties using the proposed model is presented and discussed in detail.

Short flowers for long tongues: Functional specialization in a nocturnal pollination network of an asclepiad in long‐tongued hawkmoths

AbstractSince Darwin, very long and narrow floral tubes have been known to represent the main floral morphological feature for specialized long‐tongued hawkmoth pollination. However, specialization may be driven by other contrivances instead of floral tube morphology. Asclepiads are plants with a complex floral morphology where primary hawkmoth pollination had never been described. We detailed here the intricate pollination mechanism of the South American asclepiad Schubertia grandiflora, where functional specialization on long‐tongued hawkmoth pollinators occurs despite the short floral tube of this species. We studied two plant populations in the Brazilian Cerrado and recorded floral visitors using different approaches, such as light‐trapped hawkmoths for pollen analysis, direct field observations, and IR motion‐activated cameras. Finally, using a community‐level approach we applied an ecological network analysis to identify the realized pollinator niche of S. grandiflora among the available niches in the pollinator community. Throughout a period of 17 years, long‐tongued hawkmoths were consistently recorded as the main floral visitors and the only effective pollinators of S. grandiflora. Flowers rely on highly modified corona and gynostegium, and enlarged nectar chambers, to drive visitors and pollination mechanism. Despite its relative short‐tube, network analysis placed S. grandiflora in the module including exclusively long‐tongued hawkmoth pollinators and the most phenotypically specialized sphingophilous plants in the community. These results represent the first example of functional specialization in long‐tongued hawkmoths in an asclepiad species. However, this specialization is uncoupled from the long floral tubes historically associated with the sphingophily syndrome.Abstract in Portuguese is available with online material.

Using the silicon (luminal cast plastination technique) for the lower respiratory tract in sheep as an alternative to cement

The lower respiratory tract of sheep was studied to determine the torsion and branching of the bronchial tree. The respiratory system of ruminants and all living organisms is one of the most important organs in the body that controls the amount of gas exchange between the heart and lungs through the airways, it is clear that in sheep it consists of a narrow bronchial tube that reaches the extent of lung tissue repercussions. He used silicon, water, acid, and at room temperature, and the substance was injected with an injection gun through the trachea and was pushed gently to spread and distribute in all parts of the lungs with moderate manual pressure. The results showed that the mold shape in the lung and the bronchial branches of the bronchi is solid and anti-erosion with a very clear and three-dimensional appearance, easy to handle, store and carry for study and presentation purposes in scientific museums, and in scientific presentations as an anatomical method for large-scale teaching.

Viscous flow fields in hyperelastic chambers

Viscous flows in hyperelastic chambers are relevant to many biological phenomena such as inhalation into the lung's acinar region, and medical applications such as the inflation of a small chamber in minimally invasive procedures. In this work, we analytically study the viscous flow and elastic deformation created due to inflation of such spherical chambers from one or two inlets. Our investigation considers the shell's constitutive hyperelastic law coupled with the flow dynamics inside the chamber. For the case of a narrow tube filling a larger chamber, the pressure within the chamber involves a large spatially uniform part, and a small-order correction. We derive a closed-form expression for the inflation dynamics, accounting for the effect of elastic bistability. Interestingly, the obtained pressure distribution shows that the maximal pressure on the chamber's surface is greater than the pressure at the entrance to the chamber. The calculated series solution of the velocity and pressure fields during inflation is verified by using a fully coupled finite element scheme, resulting in excellent agreement. Our results allow the estimation of the chamber's viscous resistance at different pressures, thus enabling us to model the process of inflation and deflation.

Electron Beam Propagation in a Metal Tube at 1–10-Pa Pressures

Some features of electron-beam propagation through a narrow metal tube at a gas pressure of 1–10 Pa have been investigated. A forevacuum-pressure, plasma-cathode electron source was used to generate the electron beam. The results obtained are described and compared with the case of electron-beam propagation in free space. A comparison shows that the tube makes it difficult for the beam to pass. Calculations based on the Rutherford scattering and Monte Carlo method show satisfactory agreement with experimental results.

Magnetic Peristaltic Ciliary Flow Regulates an Embryo Growth in the Human Fallopian Tube

The flow transport behavior in a peristaltic-ciliary fallopian tube in the human system caused by a sinusoidal pressure gradient due to magnetic lines of force has been investigated. A descriptive prototype model is established and presented in cylindrical coordinates for the fallopian tapered tubal linearly viscous fluid influenced by an external magnetic force in the human body. Under the wavelength approximation, the consequential partial differential equations governing this biological phenomenon are solved analytically. The solutions obtained are presented in modified Bessel functions of zeroth order of the first kind. Also, solutions are obtained for the velocity components along the axial and the radial directions, pressure gradient, pressure differences over a wavelength, and the stream function. The impacts of the various physical quantities of interest on the momentum transport, wavy curve patterns depicting the velocity range, and the pressure change are plotted. A comparison study of peristaltic, peristaltic-ciliary, and magnetic peristaltic-ciliary flows is also presented as a special case. Furthermore, the embryo's development in the interior of the narrow fallopian tube intramural fluid coming from the ampulla is discussed.

Baseball bat-like gastric tube for end-to-side oesophageal-gastric anastomosis decreased risks of anastomotic leakage after oesophagectomy for oesophageal cancer: A retrospective propensity score matched comparative study with 613 patients

PurposeTo investigate the relationship between baseball bat-like gastric tubes for end-to-side oesophageal-gastric anastomosis and occurrence of anastomotic leakage after oesophagectomy for oesophageal cancer. MethodsFrom July 2019 to June 2021, 613 patients with bat-like or narrow gastric tubes for end-to-side oesophageal-gastric anastomosis in oesophagectomy were retrospectively enrolled, in which 120 patients had narrow gastric tubes and 493 had bat-like gastric tubes. Clinical data including baseline characteristics, in-hospital variables and follow-up outcomes were collected. ResultsHigher occurrence of anastomotic leak was observed in the narrow group in the unmatched cohort (14.2%, 17/120 vs. 7.3%, 36/493; P = 0.016) or the matched cohort after Propensity Score Matching (PSM) analysis (14.2%, 17/120 vs. 7.5%, 27/360, P = 0.028) when compared to the bat-like group; Multivariable analysis for risk factors of postoperative anastomotic leak in the unmatched cohort showed that the use of bat-like gastric tube was an independent protective factor (OR: 0.502, 95% CI: 0.270–0.935, P = 0.030). ConclusionsBat-like gastric tube can be used for end-to-side oesophageal-gastric anastomosis in oesophagectomy. This technique by improving blood supply to the area distal to the anastomosis decreased the incidence of anastomotic leak.

On potentials of Itô’s Processes with Drift in Ld+ 1

This paper is a natural continuation of Krylov (2020), where strong Markov processes are constructed in the time inhomogeneous setting with Borel measurable uniformly bounded and uniformly nondegenerate diffusion and drift in \(L_{d+1}(\mathbb {R}^{d+1})\). Here we study some properties of these processes such as the probability to pass through narrow tubes, higher summability of Green’s functions, and so on. The results seem to be new even if the diffusion is constant.

Principles of microtubule polarity in linear cells

The microtubule cytoskeleton is critical for maintenance of long and long-lived neurons. The overlapping array of microtubules extends from the major site of synthesis in the cell body to the far reaches of axons and dendrites. New materials are transported from the cell body along these neuronal roads by motor proteins, and building blocks and information about the state of affairs in other parts of the cell are returned by motors moving in the opposite direction. As motor proteins walk only in one direction along microtubules, the combination of correct motor and correctly oriented microtubules is essential for moving cargoes in the right direction. In this review, we focus on how microtubule polarity is established and maintained in neurons. At first thought, it seems that figuring out how microtubules are organized in neurons should be simple. After all, microtubules are essentially sticks with a slow-growing minus end and faster-growing plus end, and arranging sticks within the constrained narrow tubes of axons and dendrites should be straightforward. It is therefore quite surprising how many mechanisms contribute to making sure they are arranged in the correct polarity. Some of these mechanisms operate to generate plus-end-out polarity of axons, and others control mixed or minus-end-out dendrites.

Triboelectric effects in catalyst feeders of fluidized-bed polymerization reactors

Solid material in fluidized-bed polymerization reactors consists of two components with different triboelectric properties. The main material is a granular polymer with the particle size from ∼100 to >1000 μm. The second component, very small in volume, is fresh catalyst, spherical particles with the diameter from 20 to 40 μm. Small loads of catalyst particles are periodically fed into the reactors through narrow metal tubes with a gas flow (nitrogen or monomer).This catalyst injection process leads to accumulation of a significant electric charge on the catalyst particles. This paper describes results of laboratory experiments aimed at determining sources of electrostatics generation in spherical catalyst particles passing through narrow tubes, a possible mechanism of the charging and methods of its mitigation.

Laparoscopic Sleeve Gastrectomy Outcomes

Introduction: Sleeve gastrectomy was first defined in 1990 as a part of the duodenal switch procedure with the formation of a narrow stomach tube along the small curvature of the stomach. Later, researchers proposed that Laparoscopic leave gastrectomy (LSG) reduced the risk profile of the duodenal switch procedure in high risk patients. Additionally, LSG was accepted as a rapid single bariatric surgical procedure due to its simplicity and efficacy. The aim of this study was to describe the outcomes of LSG at a single bariatric unit in King Salman North West Armed Forced Hospital (KSAFH), Tabuk, Saudi Arabia. Objective: To compare outcomes of primary LSG regarding pre and post operative sleep apnea, diabetes mellitus (DM), arterial hypertension (HTN), bronchial asthma, female urinary incontinence, infertility, and gastroesophageal reflux (GERD). We will assess our complications according to the Clavein-Dindo classification. We reviewed the medical records of patients who underwent LSG in King Salman Armed Forces Hospital from 1/1/2015 till 31/6/2017. Methods: This retrospective comparative study is performed in the Department of Surgery, KSAFH. All patients are instructed for follow-up at 1 week and 1, 3, 6, 12, 18, 24 months postoperatively. Laboratory tests are requested every 6 months post op. Improvement of Comorbidities assessed post-operatively. Surgical Complications reported according to the Clavein-Dindo classification. Our results were compared with international studies. Inclusion criteria (more than 14 years, morbid obese with BMI > 40 and obese class 11 with comorbidities). Exclusion criteria (less than 14 years, BMI Results: A total of 127 patients underwent LSG at King Salman Armed Forces Hospital from 1/1/2015 till 31/5/2017. Of these, 40 were male (31.5%) and 87 were female (68.5%). The mean age was 35 years. Comorbidities included diabetes 31 (24.4%),

Vertical quasistatic Poiseuille flow: Theory and experiment

As a viscous fluid drains from the bottom of a wide-mouthed reservoir through a narrow vertical tube, the symmetric flow within the tube, known as Poiseuille flow, is quickly established. Since the pressure provided by the fluid in the reservoir changes slowly in time, the flow is quasistatically time dependent. Our theoretical model of this process relates the time dependence of the height of the fluid in the reservoir to the dimensions of the tube and the kinetic viscosity of the fluid. We construct an apparatus from inexpensive and easily procured materials (plastic containers, steel straws, glue, adhesive putty, and a supply of pure glycerin) in order to test our model and find good agreement between the theory and the experiment.

An Analytical Study of Creeping Flow of a Second‐Order Fluid through a Small Diameter Leaky Tube with Linearly Diminishing Absorption

This study is focused on investigating the effects of linear absorption parameter on creeping flow of a second‐order fluid through a narrow leaky tube. These flows are experienced in several biological and industrial procedures, for instance, in proximal convoluted tubule of a human kidney, in hemodialysis devices, in filtration processes of food industry, journal bearing, and slide bearing. Inertial effects are neglected due to creeping motion assumption and low Reynolds number. Langlois recursive approach method is used to linearize the governing compatibility equation and to obtain an approximate analytical solution by reverse solution method. Analytical expressions for various physically important quantities like velocity profile, bulk flow, mean pressure drop in longitudinal direction, wall shear stress, leakage flux, fractional absorption, and stream function are obtained in dimensionless form. The obtained solution shows great similarity with the already available work in the literature. Variation in flow variables with linear absorption parameter is analysed in detail. The special case of uniform absorption in creeping motion of second‐order fluid is presented in a separate section. It is noticed that velocity field, in case of uniform absorption, is independent of non‐Newtonian parameters. Therefore, it is asserted that any two dimensional axisymmetric Newtonian velocity fields is also a solution for second‐order fluids with identical boundary conditions.

Histological Feature of Uterus and Uterine Tube During Late Period of Pregnancy in Rabbits

Current work was conducted to investigate the histological architecture of the uterine tube and uterus during the period of late pregnancy in rabbits. Twelve adult local breed rabbits were used. The samples from different parts of the uterine tube were prepared for histological study after staining with H&E, Masson’s trichrome and combine Alcian blue (pH2.5)-PAS. The pre ampulla was a narrow tube and its tunica mucosa had slightly long simple mucosal folds lined by pseudostratified columnar epithelium, the ampulla had a wide lumen and its tunica mucosa displayed several highly tall branched mucosal folds with few short simple folds while the isthmus was the narrowest region and its tunica mucosa displayed few of tall and short simple mucosal folds. The mucosa of three parts of the uterine tube was lined by pseudostratified columnar epithelium which is composed of three types of cells: mucous secretory cells, non-secretory cells and basal cells, the mucous secretory cells were the predominant type and revealed secretory activities. The lamina propria-submucosa of the uterine tube was composed of cellular connective tissue and tunica muscularis. The uterus had a very thick wall with well-recognized endometrium and myometrium, the endometrium was composed of many-branched and simple endometrial folds that were covered by multinucleated syncytial cells and simple cuboidal epithelial cells. Lamina propria was composed of loose connective tissue had scattered groups of well growing simple uterine glands that showed secretory activities. The current result showed that the uterus during the late period of pregnancy was differed from those of non-pregnant rabbits, while the uterine tube at late pregnancy has a structure that appeared prepared for the next physiological period.

The Pellicle-Another Strategy of the Root Apex Protection against Mechanical Stress?

In grasses, the apical part of the root is covered by a two-layered deposit of extracellular material, the pellicle, which together with the outer periclinal wall of protodermal cells forms the three-layered epidermal surface. In this study, the effect of mechanical stress on the pellicle was examined. An experiment was performed, in which maize roots were grown in narrow diameter plastic tubes with conical endings for 24 h. Two groups of experimental roots were included in the analysis: stressed (S) roots, whose tips did not grow out of the tubes, and recovering (R) roots, whose apices grew out of the tube. Control (C) roots grew freely between the layers of moist filter paper. Scanning electron microscopy and confocal microscopy analysis revealed microdamage in all the layers of the epidermal surface of S roots, however, protodermal cells in the meristematic zone remained viable. The outermost pellicle layer was twice as thick as in C roots. In R roots, large areas of dead cells were observed between the meristematic zone and the transition zone. The pellicle was defective with a discontinuous and irregular outermost layer. In the meristematic zone the pellicle was undamaged and the protodermal cells were intact. The results lead to the conclusion that the pellicle may prevent damage to protodermal cells, thus protecting the root apical meristem from the negative effects of mechano-stress.

Acoustic absorption modeling of single and multiple coiled-up resonators

This work proposes an improved design procedure of sound absorption metamaterials consisting of acoustic coiled-up quarter-wave resonators that fit into a limited space, in order to broad the range of possible applications even in the low-frequency regime. Different types of models were used to understand the propagation of sound in long, narrow, and square-section tubes, including the visco-thermal loss within the structures for accurate modeling. An analytical model, which includes the definition of the different loss contributions with equivalent fluid models, has been developed: the Johnson-Champoux-Allard model for inlet losses and the “Narrow Region” model for visco-thermal loss along the tubes. A geometric parameterization procedure, for maximizing acoustic absorption at certain target frequencies, was carried out. To validate the theoretical acoustic absorption predictions, the 3D printing technique was used to fabricate samples in a plastic material (PLA) for normal incidence sound absorption coefficient measurements. Moreover, systems containing several quarter-wave resonators of different dimensions coupled in parallel or in series were designed, with the aim of broadening the absorption band; in this case, for practical reasons, only the medium-high frequency regimes were experimentally investigated.